In the less innovative variety of Japanese the following alternations occur:
チ for ティ ジ for ディ ツ for トゥ ズ for ドゥ
チ for チェ セ for シェ ゼ for ジェ ハ for ファ
ヒ for フィ ヘ for フェ ホ for フォ
"...one-fourth of all the characters used in modern Japanese occur in three-fourths of all the most frequently occurring words. This means that by concentrating on learning approximately 500 select characters, the student is assured of being able to read 75% of all the high-frequency words he will encounter in modern literature." - The Kanji Way to Japanese Language Power.